Nickel electrodeposition



United States Patent C) No Drawing. Application February 16, 1954, Serial No. 410,713

9 Claims. (Cl. 204-49) This invention relates to electrodeposition of nickel and more specifically to a process for producing electrodeposits of greatly increased brightness and smoothness, as taken from the plating solution, without buifing or polishing of any sort.

This application is a continuation-in-part of our copending application, serial No. 278,957, filed March 27, 1952, and our copending application, serial No. 338,560, filed February 24, 1953, .which was a continuation-in-part of application serial No. 278,958, filed March 27, 1952, all now abandoned.

This invention is primarily concerned with the fact that although electrodeposits taken from acid nickel plating solutions containing coumarin exhibit extraordinary smoothness they are only semi-bright, and attempts to increase their brightness by the use of addition agents of the type of saccharin or naphthalene sulfonic acids result in improved brightness with loss of smoothness when the surface being coated is quite smooth, and can result in decrease in both smoothness and brightness when the surface to be coated is quite rough. I-t'was found, for-example, that when a aqueous, acid solution containing 240 grams per liter of nickel sulfate heptahydr'ate, 40 grams per liter of nickel chloride hexahydrate and 40 grams per liter of boric acid was utilized and coumarin was used in concentration of 0.25 gram per liter as the'sole addition agent, a semi-bright deposit was obtained having a smoothness increase over the base metal of approximately 4 microinches where the base metal had a smoothness in the order of 6 *to 10 microinches, measurements having been made with the Brush surface analyzer. Such an increase in smoothness is remarkable, and :this property of coumarin has formed the basis of a commercial semi-bright solution now being widely used. When the attempt was made to increase the brightness by the addition of agents such as saccharin of naphthalene sulfonic "acids, it was found that increased brightness was secured, but at the cost of a part of the smoothing action of the coumarin. For example, it was found that when the above described solution was varied by adding 3.5 grams per liter of naphthalene disulfonic acid an increase in brightness was secured, but the gain in smoothness over the base metal was only about 2.2 microinches, the same ltype of base metal being used. If, instead of using naphthalenesulfonic acids, saccharin was used to improve the brightness, improved brightness was obtained and the gain in smoothness was about the same. Many other sulfonic acids and sulfonamides show similar results. When the surface to be coated is not so smooth, e. g. 20 to 29 R. M. S. as shown by the Brush surface analyzer the loss of the smoothing action may be so great as to overshadow the tendency toward increased brightness and actually appear to decrease the lusterof the deposit.

In accordance with the present invention it has now beendiscovered that a largevportion of the lost smoothing action :just described can berestoredsif there is added, in addition to the coumarin, not only an aromatic sul- 2 fonamide, but also one or more of certain organic, levelmg addition agents of the' following class:

Quaternary nitrogen compounds containing'the grouping and at least one aliphatic carbon atom attached to the nitrogen of said group. This group maybe substituted to form a double ring structure :of the form 0:0 I '(quinolinium) and one or more hydrogen atoms may be replaced by methyl or ethyl or other substituents. Preferably the compound may be of the bis-pyridinium or bis-lsoquinolinium type joined by a carbon or carbon and oxygen chain such as (CHzM-or (CH2)1LO(CH2)1L .As examples may be mentioned, (a) .N,N-(oxydiethylene) -bis isoquinolinium salts (b) N,N-(oxydiethylene) -bis pyridinium salts '(c) N-carboxymethyl pyridinium salts (d) N,N-(oxydimethylene)-bis-pyridinium salts e) Quinaldine methyl sulfate (f) p-Xylylene-pyridinium salts (g) N-( 2-ehloroa1lyl) pyridinium salts (h) N-methallyl pyridinium salts '(i) N,N-methylene-bis-pyridinium salts (j) N-(carboxy isobutyl) pyridinium salts.

While these leveling agents do not completely restore the full smoothing action of coumarin, they do, in someinstances restore a large portion of it.

The preferredacid nickel solution in connection with which the invention may be realized is an aqueous solution containing nickel sulfate equivalent to from 100 to 400 grams per liter of nickel sulfate heptahydrate, nickel chloride equivalent to from 10 to grams per liter of nickel chloride hexa-hydrate, and from 10 to 50 grams .per liter, :preferably 15 to 40 grams per liter, of boric acid or other buffer such as formic acid or citric acid. To this fundamental solution there may be added in accordance withthe present invention one or more aromatic sulfonamides to a concentration from /2 gram per liter to saturation, one or more coumarin compounds to a concentration from 0.01 to 0.5 gram per liter, and one or more leveling agents of the above indicated class in concentrations less than half a gram .per liter, for example, from 0.0005 to 0.3 gram per liter. The concentrations of these compounds required for best results will be within the ranges indicated in the respective tables opposite each of said compounds, and very desirably will be approximately the specific concentration set forth opposite each compound in the tables.

The compounds listed in Table I are examples of sulfur compounds which when used in connection with coumarin and certain coumarin derivatives produce an increase in brightness with some loss in smoothness. Numerous other similar compounds produce the same effect in varying degree. They are aromatic sulfonamides and 'sulfimides. The compounds of Table II are examples of coumarin compounds which can be used. Alkyl and acyl .derivativesof coumarin having 1 to 4 carbon atoms, and the chlorine and carboxy derivatives thereof are suitable. Thev compounds listed in Table III are examples of .organiccompounds effective to increase smoothing power (and brightness) of coumarin 3 type smoothing agents lost by the addition of sulfur compounds of the type of those listed in Table I. Coumarin sulfonic acids are not equivalent to the above indicated coumarin compounds.

Preferably, the solutions are operated in pH range from 2.5 to 4.5, the temperature is maintained within the range from 110 F. to 160 F., and the cathode current density is maintained within the range from 5 to 100 a. s. f.

Formaldehyde may be used in the above described solutions at a concentration of from 0.05 to 0.5 gram per liter for the purpose of retarding or minimizing the effect of breakdown products of coumarin or derivatives such as listed in Table II.

Specific examples which have yielded excellent results are indicated in Table IV.

Other basic solutions capable of yielding nickel ions for electrodeposition may be employed. Preferably there should be present in the solution at least one nickel salt of the class consisting of nickel sulfate, nickel chloride, nickel fiuoborate and nickel sulfamate. The nickel ion concentration should in any case be within the range which would result from the presence of from 100 to 400 grams per liter of NiSO4.7H2O.

Table 1 Optimum Preferred Range, Concentrag./l. tion, g./l.

(1) Benzene sulfonamide (PhSOZNH2) 0. 5 to 3.0 1. (2) p-Toluene sultonarnide (CH3CQH4SO2' NHr) 0.5130 3.0 1.0 (3) Sacchariu (o-benzosulfirnld) 0. to 3.0 1, 0 (4) Dtbenzene sulfonamide (PhSOzNHSOz- Ph) and its mono-and-dichlor0 derivatives" 0. 5 to 5.0 1. 0 (5) p-Benzene-bls (N-sylphonylbenzenesul- Ph 0.511000 1.0 26) N-ethane sulionyl benzene sulfonnmide- 0. 5 to 5.0 1.0

7) Monoand di-chlorobenzene su]fonan1ldes 0. 5 to 5. 0 1.0 (8) Monoand di-chloro derivatives of (2) and (5) above 0. 5 to 5.0 .0 (9) Bi-dibenzenesulfonamide (PhSOzNHSOfi' otniotrnsomnsogrm O. 5 to 5. 0 1.0 (10) Monoand di-chloro derivatives 01 (9) above 0. 5 to 5.0 1.0 (11) Dlbenzene sulfouamide ether (PhSOz NHS01CBE4OC5H4S02NHSO2P11) 0. 5 to 5.0 1.0

Table II Preferred Range, g./1. Concentration g./l.

Cournarln 0.05 to 0.25 0.1 3-Chloro couniarin 0. 05 to 0.25 0.1 6-Chloro eoumarin 0.05 to 0.25 0.1 4-methyl eoumnrln 0.05 to 0.25 0. 1 fi-carboxy cournarim; 0.05 to 0.25 0.1

Table III Preferred Range, g./l. Concentration, g./l.

(1) N,N-(oxydiethylene)-bis-isoquin0- linium chloride 0.003 to 0. 01 0. 005 (2) N,N-(qxydiethylene)-bis pyridinium ch r1 0 0.003 to 0. 01 0.007 (3) N-eerboxymethyl pyridinium chloride 0. 25 to 0.6 0. 4 (4) N,N-(oxydimethy1ene)-bis-pyridinrid 0.05 to 0.1 0. 08

0.05 to 0. 1 0. 08 (6) p-Xylylene pyridinium chlori e.. 0.0025 to 0.015 0.005 (7) N-(2'ohloroallyl) pyridinium chloride 0.05 to 0.12 0.08 (8) N-mcthallyl pyridinium chloride--. 0. 05 to 0. 12 0.08 (9) N,N methylene bis pyridinium chloride 0.05 to 0. 15 0.08 (10) N-(carboxy lsobutyl) pyridinium chloride 0 03 to 0 1 0.05

4 Table IV Grams per Liter NiSOtJH O giclzfiHzoflq- Dibenzene sultonamide. Bi-dibenzene sultonamide N,N-(oxydiethylene)-bispyridinium bromide N-cgrboxymethyl pyridinium chlorl e (at O l C=C one thereof being selected from the class consisting of coumarin and its alkyl, acyl, chlorine and carboxy derivatives and a third thereof being a quaternary nitrogen compound containing the grouping 6:5 -C N+ o-o l and having at least one aliphatic carbon atom attached to the nitrogen atom of said group, said first mentioned addition agent being present in concentration from onehalf gram per liter to saturation, said second mentioned addition agent being present in concentration from 0.01 to 0.5 gram per liter and said third mentioned addition agent being present in concentration from 0.0005 to 0.3 gram per liter.

2. A process for producing bright, smooth electrodeposits of nickel comprising electrolyzing between an anode and a cathode a solution containing nickel sulfate equivalent to from to 400 grams per liter of nickel sulfate heptahydrate, nickel chloride equivalent to from 10 to 75 grams per liter of nickel chloride hexahydrate and a group of three cooperating addition agents, one of said addition agents being an organic sulfur compound containing the group one thereof being selected from the class consisting of coumarin and its alkyl, acyl, chlorine and carboxy derivatives and a third thereof being a quaternary nitrogen compound containing the grouping addition agent being present in concentration from 0.01

to 0.5 gram per liter and said third mentioned addition agent being present in concentration from 0.0005 to 0.3 gram per liter.

3. A process according to claim 2 wherein said solution contains from 10 to 50 grams per liter of boric acid.

4. The invention as defined in claim 2 wherein said quaternary nitrogen compound is a bis-pyridinium compound.

5. The invention defined in claim 2 wherein said organic sulfur compound is bidibenzene sulfonamide.

6. The invention as defined in claim 2 wherein said quaternary nitrogen compound is an N,N'-(oxydiethylene) -bis pyridinium compound.

7. The invention as defined in claim 2 wherein said quaternary nitrogen compound is an N,N'-(oxydiethylenc) -bis isoquinolinium compound.

8. The invention as defined in claim 2 wherein said quaternary nitrogen compound is an N,N'-(oxydiethylene)-bis pyridinium compound and said organic sulfur compound is bidibenzene sulfonamide.

9. The invention as defined in claim 2 wherein said quaternary nitrogen compound is an N,N-(oxydiethy1- ene)-bis isoquinolinium compound and said organic sulfur compound is bidibenzene sulfonamide.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A SOLUTION FOR ELECTRODEPOSITION OF NICKEL IN THE FORM OF BRIGHT AND SMOOTH DEPOSITS, SAID SOLUTION CONTAINING A NICKEL ION YIELDING COMPOUND OF THE CLASS CONSISTING OF NICKEL SULFATE, NICKEL CHLORIDE, NICKEL SULFAMATE AND NICKEL FLUOBORATE TOGETHER WITH COOPERATING ADDITION AGENTS, ONE OF SAID ADDITION AGENTS BEING AN ORGANIC SULFUR COMPOUND CONTAINING THE GROUP 